Here is the full list of all 32 Deadlings: Rotten Edition achievements.
Complete phase 3.
Discover a freezing freezers.
Complete level 04 using one zombie.
Complete level 14 in less than 10 seconds.
Discover an awesome portals!
Collect 100 stars.
Finish 20 levels without killing a single zombie.
Complete phase 2.
Kill the zombie with the other zombie.
Collect 800 brains.
Complete 5 levels in Nightmare Mode.
Collect 50 stars.
Discover a deadly lasers.
Unlock the Lazybrain.
Complete phase 1.
Collect 400 brains.
Kill over 100 zombies.
Unlock the Gasfat.
Collect 150 brains.
Unlock the Creep.
Complete phase 4.
Discover a crazy mutators.
Complete all levels in Nightmare Mode with maximum rank.
Complete 20 levels in Nightmare Mode.
Complete 45 levels in Nightmare Mode.
Complete 60 levels in Nightmare Mode.
Collect 150 stars.
Collect 200 stars.
Complete all levels in Normal Mode with maximum rank.
Complete all bonus levels.
Complete all bonus levels with maximum rank.
Complete bonus level 10.